The invention relates to a safety device for a valve inset located in a discharge aperture of a pressurized beverage container, in particular a beer keg, comprising a housing, a rise pipe, a base plate and, an external compression spring resting by one end against the base plate and by another end against a seal. A locking component is pivotally mounted between the external compression spring and the base plate such that during insertion it moves out of the way relative to a dispensing aperture of the pressurized container or keg and in the operational position it engages from behind an inner rim of the dispensing aperture.
Conventional safety devices of the above type are known in a variety of designs. They are used to seal the dispensing aperture of a pressurized beverage container, in particular a beer keg, after it has been filled, and are subsequently connected to a tap when dispensing the beverage. When the beverage containers are readied at the factory, the safety devices are each inserted into a dispensing aperture of each container. As a rule, the component of the beverage container which herein is called for simplicity merely the keg dispensing aperture generally comprises a pipe stub which enters at least partly into the keg and is fitted with an internal thread in the vicinity of the outer upper end so that the safety device, in turn fitted with a corresponding outer thread, can be screwed tightly into the safety device or safety insert. Thereupon the beverage keg undergoes further processing steps, in particular pressure tests for proper sealing, cleaning etc., until finally the beverage keg is filled with a beverage, at another keg location, namely through a separate feed aperture, and then is sealed.
In practice numerous accidents have taken place mostly because of improper handling of the safety device or valve inset in the keg dispensing aperture. If for instance the heretofore widely used conventional valve insets are being unscrewed from the filled or partly filled beverage keg, then the internal pressure in the keg may cause the entire system to fly out at high speed jeopardizing and/or injuring the operator.
Regulations have been issued to prevent such dangers, namely that the valve insets must be fitted with safety devices which always shall preclude the valve inset from being propelled out of the keg if improperly handled. As a result of these regulations, many varied and mostly highly complex designs have been suggested. Illustratively, a safety device used in practice comprises a bayonet slotted plate in the valve inset, the plate in turn being fitted with a hook which in the operational position will act underneath the lower or the inner rim of a pipe stub at the keg dispensing aperture. However, such a design incurs the drawback that the safety device together with its individual components must be inserted while in the disassembled condition because the size of the bayonet plate exceeds the diameter of the keg dispensing aperture or of the pipe stub. Therefore, the bayonet plate must be moved by itself and obliquely through the dispensing aperture inside the pipe stub and thereupon it must be pivoted into the proper position, whereafter the actual assembly of the safety device must be carried out while the bayonet system then locks. With the large-scale handling of the beverage kegs in the beverage industry, such handling is extraordinarily laborious and time-consuming.
British patent document 21 88 040 describes a safety device similar to the one discussed above. In this design the locking component proper is an outwardly projecting hook integral with the bayonet plate. Accordingly, only partial assembly of the safety device may be carried out initially, that is, a partial assembly of the central pipe with a sealing annulus, compression spring and an initially loose bayonet plate. Because of the radial projection of the locking component, the insertion procedure through the dispensing aperture of the cask can be implemented only by keeping the bayonet plate and the central pipe oblique. Thereupon the final assembly of the safety device is carried out by depositing a separate head part with a cylindrical pipe stub comprising L-shaped slots at its inside end which must receive radial projections of the bayonet plate. Only after such procedure is it possible to definitively screw the safety device into the keg dispensing aperture. This design and its assembly is cumbersome and time-consuming, the more so because the compression spring must be compressed when being mounted to the keg in order to make the bayonet plate engage.
A similar safety device is disclosed in WO 91/026 94-A1. Therein the locking component consists of a comparatively long axial tang with an integral ring at its upper end which in turn is held by a compression spring. The lower tang end is bent outward and comprises a bracket which is bent radially outward. Again, the configuration of the locking component entails initial assembly in an oblique central pipe position as well as of the surrounding parts before the housing can be righted, axially inserted and lastly screwed in place.
Finally, German Offenlegungsschrift 38 44 428 discloses anchoring systems for tap pipes in beer kegs. Three circumferentially distributed and axially parallel bars are present on an upper sealing component, angled arms running obliquely upward and outward being linked in a suitable manner to the lower ends of said bars and being affixed through windows in the pipe wall of the head piece. The free ends of these arms point to the inside surface of the vessel neck and thereby the head piece cannot be rotationally loosened from the keg.
Further safety devices are known from the British patent document 2,209,740 and from U.S. Pat. No. 1,003,447.
German patent document 41 14 604 A1 discloses a safety device of the type initially described herein. While this safety device is easily assembled and easily inserted, it was found that the removal from the keg dispensing aperture is practically excessively cumbersome and time-consuming.